FIG. 1 is a conceptual view illustrating a construction of a conventional ATSC-MH (Advanced Television System Committee-Mobile Handheld) broadcast receiving system.
FIG. 2 is a conceptual view illustrating a construction of a conventional ATSC (Advanced Television System Committee) broadcast system.
Referring to FIG. 1, the conventional ATSC-MH broadcast receiving system includes a tuner 11, a demodulator 12, an equalizer 13, a known sequence detector 14, a block decoder 15, a main data processing part 20, and a mobile data processing part 30.
The tuner 11 tunes an RF signal to down-convert the RF signal to an intermediate frequency signal (IF signal), and then outputs converted signal to the demodulator 12. The demodulator 12 performs automatic gain control, carrier recovery, and timing recovery for an incoming IF signal to convert the IF signal into a base band signal, and then outputs the converted signal to the known sequence detector 14. The equalizer 13 compensates for distortion on a channel included in the demodulated signal and then outputs the result signal to the block decoder 15.
Meanwhile, in case where the incoming data corresponds to main service data having been subjected to trellis encoding alone, the block decoder 15 performs trellis decoding for the incoming data, and then inputs the result data to the main data processing part 20. In case where the incoming data corresponds to mobile data subjected to additional encoding and trellis encoding by a transmission system, the block decoder 15 performs the processes of the transmission system reversely, additional decoding, and trellis decoding for the mobile data, and then inputs the result data to the mobile data processing part 30. The mobile data after the block decoder 15 has the same data structure as MPH Group format after data interleaver of the transmission system. The mobile data is generated into mobile service data after passing through a data deformatter 21, an RS frame decoder 22, and a derandomizer 23 of the mobile data processing part.
Meanwhile, the main data passing through the block decoder 15 is generated into main service data after passing through a data de-interleaver 31, an RS decoder 32, and a data derandomizer 33, which are the same constructions as those of the conventional ATSC broadcast receiver (see FIG. 2).
In the case of the conventional ATSC broadcast system shown in FIG. 2, the ATSC broadcast receiver does not include a block decoder and a mobile data processing part, but includes a trellis decoder 51, a data de-interleaver 52, an RS decoder 53, and a data de-randomizer 55. The ATSC broadcast receiver is ready to receive an ATSC-MH broadcasting signal to generate main service data from the received ATSC-MH broadcasting signal, as in the case of the conventional ATSC broadcasting signal. Each of the by-product data generated from the main data has the same structure as that of the incoming data of the trellis encoder 61, the data interleaver 62, the RS encoder 63, and the data randomizer 65 of the transmission side, respectively.
However, the conventional ATSC broadcast receiver has problems as follows.
Though the conventional ATSC broadcast receiver 50 receives and decodes the ATSC-MH broadcasting signal comprising mobile data, it was impossible to separate the by-product mobile data before the last result of main data processing (i.e. data before the data de-randomizer) for most of the conventional ATSC receivers. This is because the main data processing part in the conventional ATSC broadcast receiver 50 has manufactured in the form of one chip semiconductor and has come into wide use. Therefore, it is impossible to be ready to receive ATSC-MH mobile broadcast through the conventional ATSC broadcast receiver 50, by adding the mobile data processing part 20 to it. Furthermore, in order to receive ATSC-MH mobile broadcast, users are required to buy a separate mobile broadcast receiver.